Three Millennia of Humans Reshaping the Earth

The Anthropocene — the current geologic epoch, defined by human influence over the planet — began not decades ago, or even in the 19th century, but by at least 3,000 years ago. Over this period, humans have developed increasingly innovative methods of using ecological landscapes that allowed them to exceed previous natural limits and even reduce relative impacts. In order to cultivate a hospitable Anthropocene we must embrace our history of shaping and caring for the Earth.

Share

Humans have been changing Earth’s landscapes at globally significant levels for at least 3000 years, and doing so by increasingly productive and efficient means, according to our new research challenging the claim that use of land by industrial civilization is destroying planetary ecology at an accelerating pace.

The paper, published this week in the journal Proceedings of the National Academy of Sciences and based on collaborative efforts of an international, interdisciplinary team of scientists including myself, demonstrates that the Anthropocene — “the age of humans” — was not born yesterday: it was created by the long-sustained efforts of our ancestors.

At stake are profound questions about the extent of human influence over the planet and the effects of large-scale ecological change on human wellbeing, environmental health, and biodiversity. Our research shows that human impact in at least one area of environmental change, land use, is much older than is generally thought and also indicative of humanity’s capacity to innovate and adapt, gaining higher yields from less land. In other words, humans have gradually diminished their use of land per capita over time.

The early history of human transformation of Earth’s ecology has long been known by archaeologists to be rich, deep, and global. Humans began profoundly altering ecosystems on most continents many thousands of years ago — even before the last ice age. Yet global change science, with its emphasis on recent rapid changes in climate caused by the burning of fossil fuels, has focused on the industrial revolution as the central cause of Earth’s transformation by humanity.

By investigating the early history of human land use quantitatively at global scale for the first time, we show that human engineering of ecosystems to sustain human populations likely changed the biosphere at globally significant levels by 3000 years ago or earlier. Long before the emergence of agriculture, human populations had already begun adapting to denser populations by increasing the productivity of their land use systems, burning forests to attract game, consuming broader diets, and propagating favored species. The emergence of agriculture only continued the trend towards increasingly productive and intensive use of the same land.

We humans in our billions could not be here today if not for the long-sustained efforts of our ancestors to make the Earth work for us. Since prehistory, we have been clearing, grazing, and tilling the soil to produce our daily bread (or daily rice, millet, or tortilla). In the process, our ancestors created the used but still thriving biosphere we now depend on – the agricultural and forested landscapes that we cannot live without. These landscapes now cover the vast majority of Earth’s surface, more than three quarters by most estimates.

Early in the process of changing ecosystems to support us, we became adapted to the ecological changes wrought by our ancestors. We depended on the management of transformed environments to survive and to thrive, and we continued to change them to meet the challenges of feeding ever greater populations from the same old land. Our species has always made a living by going beyond its environmental limits.

In some ways, little has changed as we move deeper into the Anthropocene. We continue reaping more from the same land, while our ever denser and wealthier urban populations are tending to concentrate human demands for the products of agriculture into Earth’s most productive landscapes. As a result, we stand at the crossroads of a novel opportunity — to guide our use of land towards leaving more habitat for other species.

The idea that industrial civilization has “ended nature” must be replaced by the historical reality: since prehistory our species has survived and prospered only by the engineering of ecosystems to sustain us. We live on a planet transformed by our ancestors to get us to this time of extraordinary achievement and plenty.

The challenges of our generation and those of the future are nevertheless serious: we have created some massive novel changes in the Earth system – namely rapid anthropogenic climate change driven by fossil fuel combustion – that are unprecedented. There are different paths to the future, and not all lead to a hospitable Anthropocene. But to begin the journey towards an Anthropocene that continues to support vibrant human and nonhuman life, we must embrace our history as ancestral shapers and stewards of the biosphere.